Vehicle on-board unit

ABSTRACT

A vehicle on-board unit is configured to communicate with other vehicles to increase an accuracy of a lane centerline determination of a road that the vehicle is traveling. The vehicle on-board unit basically has a vehicle path history generating section, a two-way wireless communications section and a lane centerline determining section. The vehicle path history generating section generates a host vehicle path history data indicative of a travel path of the host vehicle. The two-way wireless communications section receives a preceding vehicle message that at least includes a preceding vehicle path history data indicative of a travel path of the preceding vehicle along a lane that the host vehicle is currently traveling. The lane centerline determining section determines a lane centerline of the lane that the host vehicle is currently traveling based on the host vehicle path history data and the preceding vehicle path history data.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a vehicle on-board unit. Morespecifically, the present invention relates to a host vehicle having avehicle on-board unit that communicates with other vehicle to increasethe accuracy of a lane centerline determination of the road that thehost vehicle is traveling.

2. Background Information

Recently, vehicles are being equipped with a variety of informationalsystems such as navigation systems, Sirius and XM satellite radiosystems, two-way satellite services, built-in cell phones, DVD playersand the like. These systems are sometimes interconnected for increasedfunctionality. Various informational systems have been proposed that usewireless communications between vehicles and between infrastructures,such as roadside units. These wireless communications have a wide rangeof applications ranging from crash avoidance to entertainment systems.The type of wireless communications to be used depends on the particularapplication. Some examples of wireless technologies that are currentlyavailable include digital cellular systems, Bluetooth systems, wirelessLAN systems and dedicated short range communications (DSRC) systems.

Dedicated short range communications (DSRC) is an emerging technologythat has been recently investigated for suitability in vehicles for awide range of applications. DSRC technology will allow vehicles tocommunicate directly with other vehicles and with roadside units toexchange a wide range of information. In the United States, DSRCtechnology will use a high frequency radio transmission (5.9 GHz) thatoffers the potential to effectively support wireless data communicationsbetween vehicles, and between vehicles, roadside units and otherinfrastructure. The important feature of DSRC technology is that thelatency time between communications is very low compared to most othertechnologies that are currently available. Another important feature ofDSRC technology is the capability of conducting both point-to-pointwireless communications and broadcast wireless messages in a limitedbroadcast area.

Accordingly, wireless technology can be used to provide variousinformation from vehicle-to/from-infrastructure, and fromvehicle-to-vehicle. In vehicle safety applications, a “Common MessageSet” (CMS) would mostly likely be developed in which a prescribed set ofvehicle Parameter Identifiers (PIDs) are broadcast by each vehicle togive relevant kinematical and location information such as GPSlocation/vehicle position, vehicle speed, vehicle dimensions etc. The socalled common message set can be broadcasted in three different way,i.e., event based broadcasting, periodic broadcasting and hybrid (eventbased/periodic) broadcasting. In event based broadcasting, nocommunications are conducted until a potential safety concern (event) isdetermined to exist. Once the event occurs, event specific messages willbe sent out at a predetermined frequency (e.g., 10 Hz). In periodicbroadcasting, each vehicle will send out a “heart beat” message at apredetermined frequency (e.g., 10 Hz). This “heart beat” message willcontain all the information necessary for all the safety applications tofunction. In hybrid (event based/periodic) broadcasting, a “heart beat”message will be periodically sent at a predetermined lower frequency(e.g., 2-3 Hz) and an event specific message will be sent out once apotential safety concern (event) is determined to exist. In any case,once a potential safety concern is determined to exist, a warning systemin the vehicles would notify the driver of the potential safety concernso that the driver can take the appropriate action. Thus, whencommunications are established with between vehicles and/or roadsideunits in close proximity, this information would be communicated toprovide a complete understanding of the vehicles in the broadcast area.This information then can be used by the vehicles for both vehiclesafety applications and non-safety applications.

Recently, a Vehicle Safety Communication Consortium (VSCC) wasestablished to study safety applications of wireless communications. TheVehicle Safety Communication Consortium developed a list of safetyapplications that were believed to have the highest potential forreducing the number or mitigating crashes. During these studies, oneparticular application that was developed was called the EmergencyElectronic Brake Light application (EEBL). In the Emergency ElectronicBrake Light application, a vehicle-to-vehicle communication isestablished with an aim to prevent rear end crashes by communicating ahard braking event by a preceding vehicle to other vehicles in thevicinity. In this application, a vehicle can be notified of the hardbraking event even if the driver cannot see the brake lights of thepreceding vehicle, e.g. when a truck or a terrain obstacle is blockingthe driver's view of the brake lights of the preceding vehicle. When theEmergency Electronic Brake Light application is employed, it isimportant to be able to determine if the incoming message of a hardbraking event is relevant to the host vehicle receiving the incomingEEBL message. Thus, the EEBL message should contain all the necessaryinformation for the following vehicles to make a reliably decision. Inparticular, the EEBL incoming message can include relevant messageelements that describe the dynamics of the situation, a vehicle pathhistory (also known as breadcrumbs) and other vehicle identifying data.It has been proposed that the path history (i.e. breadcrumbs) be definedby ten breadcrumbs with 1 sec time difference between subsequentbreadcrumbs. Each breadcrumb contains location information of thevehicle so that the following vehicles can determine the relevancy ofthe incoming EEBL message. One problem with using breadcrumbs in makingthe relevancy determination of the incoming EEBL message is that thelocation information may not be sufficiently accurate to allow thefollowing vehicles to know precisely the lane of the broadcastingvehicle.

In view of the above, it will be apparent to those skilled in the artfrom this disclosure that there exists a need for an improved vehicleon-board unit that provides more precise lane information. Thisinvention addresses this need in the art as well as other needs, whichwill become apparent to those skilled in the art from this disclosure.

SUMMARY OF THE INVENTION

It has been discovered that wireless communications between vehicles canbe used in to initiate various vehicle pre-collision countermeasures.However, in order to initiate various vehicle pre-collisioncountermeasures it is important to accurately determine the lane inwhich a vehicle is traveling.

The present invention was conceived in view of the above mentioneddevelopments in vehicles and wireless communications. One object of thepresent invention is to provide a vehicle on-board unit that providesmore accurate lane information. In view of the above, a vehicle on-boardunit in accordance with one aspect of the present invention wasdeveloped in order to achieve the above mentioned object and otherobjects of the present invention. The vehicle on-board unit of thisaspect of the present invention basically comprises a vehicle pathhistory generating section, a two-way wireless communications sectionand a lane centerline determining section. The vehicle path historygenerating section is configured to generate a host vehicle path historydata indicative of a travel path of a host vehicle equipped with thevehicle on-board unit. The two-way wireless communications section isconfigured to receive a preceding vehicle message that at least includesa preceding vehicle path history data indicative of a travel path of thepreceding vehicle along a lane that the host vehicle is currentlytraveling. The lane centerline determining section is configured todetermine a lane centerline of the lane that the host vehicle iscurrently traveling based on the host vehicle path history data and thepreceding vehicle path history data.

In accordance with another aspect of the present invention, a lanecenterline determination method is provided that basically comprises:broadcasting a first vehicle path history data indicative of a travelpath of a first vehicle that has traveled along a vehicle lane;receiving the first vehicle path history data in a second vehicle thatsubsequently travels the vehicle lane relative to the first vehicle;establishing a second vehicle path history data indicative of a travelpath of the second vehicle along the vehicle lane; and determining acenterline of the lane based on the first vehicle path history data andthe second vehicle path history data.

These and other objects, features, aspects and advantages of the presentinvention will become apparent to those skilled in the art from thefollowing detailed description, which, taken in conjunction with theannexed drawings, discloses a preferred embodiment of the presentinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the attached drawings which form a part of thisoriginal disclosure:

FIG. 1 is a pictorial representation of a two-way wirelesscommunications network showing several vehicles equipped with anon-board unit capable of conducting two-way wireless communications witheach other and as well as an external server via a plurality of roadsideunits in a vehicle infrastructure system in accordance with the presentinvention;

FIG. 2 is a schematic representation of a vehicle that is equipped withthe on-board unit for conducting two-way wireless communications in thevehicle infrastructure system in accordance with the present invention;

FIG. 3 is a pictorial representation of the two-way wirelesscommunications network showing the various communications in the vehicleinfrastructure system in accordance with the present invention;

FIG. 4 is an inside elevational view of a portion of the vehicle'sinterior that is equipped with the on-board unit for conducting two-waywireless communications in the vehicle navigation system in accordancewith the present invention;

FIG. 5 is a flowchart illustrating a flow of control executed in theon-board unit in performing a lane centerline determination method inaccordance with the present invention;

FIG. 6 is a pictorial representation of the breadcrumbs by severalvehicles equipped with the on-board unit in accordance with the presentinvention;

FIG. 7 is a flowchart illustrating a flow of control executed in theon-board unit in performing an anti-tailgating method to activate brakelights in the host vehicle upon determining a vehicle travelingcondition exists that is indicative of a potentially inadequate safetyzone between the host vehicle and a following vehicle in accordance withthe present invention; and

FIG. 8 is a flowchart illustrating a flow of control executed in theon-board unit in performing a potential braking situation alert methodto alert the driver of a potential braking situation in a precedingvehicle in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Selected embodiments of the present invention will now be explained withreference to the drawings. It will be apparent to those skilled in theart from this disclosure that the following descriptions of theembodiments of the present invention are provided for illustration onlyand not for the purpose of limiting the invention as defined by theappended claims and their equivalents.

Referring initially to FIGS. 1 to 3, a two-way wireless communicationsnetwork is illustrated that forms a part of a vehicle infrastructuresystem in accordance with one embodiment of the present invention. Inthis vehicle infrastructure system, a plurality of host vehicles 10 areeach equipped with a vehicle on-board unit 12 in accordance with oneembodiment of the present invention. The two-way wireless communicationsnetwork also preferably includes one or more global positioningsatellites 14 (only one shown), and one or more roadside units 16 and abase station or external server 18. As explained below, the vehicleon-board unit 12 is configured and arranged to execute safety programsincluding a lane centerline determination feature, an anti-tailgatingfeature and a potential braking alert feature in accordance with thepresent invention. By accurately determining a lane centerline of thelane that a vehicle is traveling, the vehicle on-board unit 12 can moreaccurately determine the relevancy of an incoming message forselectively performing the anti-tailgating feature and a potentialbraking alert feature.

In this system, the term “host vehicle” refers to a vehicle among agroup of vehicles equipped with two-way wireless communications in whicha vehicle to vehicle communications are carried out in accordance withthe present invention. The term “preceding vehicle” refers to vehiclesequipped with two-way wireless communications that are located in frontof the host vehicle and traveling on the same road as the host vehicle.The term “following vehicle” refers to vehicles equipped with two-waywireless communications that are located in behind the host vehicle andtraveling on the same road as the host vehicle. The term “neighboringvehicle” refers to vehicles equipped with two-way wirelesscommunications that are located within a prescribed communication(broadcasting/receiving) area surrounding the host vehicle in which thehost vehicle is capable of either broadcasting a signal to anothervehicle within a certain range and/or receiving a signal from anothervehicle within a certain range.

Referring now to FIG. 2, the vehicle on-board unit 12 of the presentinvention basically includes a controller or control unit 20, a two-waywireless communication system 21 and a human-machine interface section22. In the present invention, the control unit 20 and the human-machineinterface section 22 cooperate together to constitute both a userinputting section and a reporting section. Also in the presentinvention, the control unit 20 and the two-way wireless communicationsystem 21 cooperate together to constitute a vehicle to vehiclecommunication section.

The two-way wireless communication system 21 is configured and arrangedsuch that the control unit 20 receives and/or sends various signals toother DSRC equipped component and systems in the communication(broadcasting/receiving) area that surrounds the host vehicle 10. Thehuman-machine interface section 22 includes a screen display 22A, anaudio speaker 22B and a plurality of manual input controls 22C that areoperatively coupled to the control unit 20. The control unit 20 is alsopreferably coupled to a global positioning system 23 (constituting anavigation unit) having a GPS unit 23A and a GPS antenna 23B. A mapdatabase and storage section 25 is also preferably provided thatcontains various data used by the control unit 20 to carry out thenavigation controls as well as implementation of various safetymeasures. The map database and storage section 25 can be manual updatedthrough removable media (CD-ROM or DVD) or automatically updated viaperiodic communications with the external server 18. The control unit20, the human-machine interface section 22, the global positioningsystem 23 and the map database and storage section 25 are operativelyconnected together to perform the various navigation functions, andthus, constitute an on-board navigation unit. Moreover, the control unit20 of the vehicle on-board unit 12 is configured to receive detectionsignals from various in-vehicle sensors including, but not limited to,an ignition switch sensor, an accessory switch sensor, a vehicle speedsensor, an acceleration sensor, etc.

Still referring now to FIG. 2, the vehicle 10 is basically aconventional vehicle which has been modified to incorporate the vehicleon-board unit 12 of the present invention. Thus, the conventional partsof the vehicle 10 will not be discussed and/or illustrated herein.Rather, only those parts that interact with the vehicle on-board unit 12will be discussed and/or illustrated herein as needed to understand thepresent invention. The vehicle 10 is provided with a steering structure26, a steering vibrating device 28, an accelerator pedal 30 operativelyconnected to a throttle valve 32, a throttle valve opening sensor 34, avisual warning indicator 36 and a pair of brake lights 38 as well asother parts not shown. The steering vibrating device 28 is operativelycontrolled by the control unit 20 to vibrate the steering wheel of thesteering structure 26 when the control unit 20 determines that it isdesirable to warn the driver of a safety concern such as a potentialbraking situation occurring in the preceding vehicle. The throttle valveopening sensor 34 is operatively connected to the control unit 20 toindicate the movement of the accelerator pedal 30 and or theopening/closing of the throttle valve 32. The visual warning indicator36 is operatively controlled by the control unit 20 to provide a visualwarning to the driver when a signal is received indicating a safetyconcern such as a potential braking situation occurring in the precedingvehicle, e.g., the releasing the accelerator pedal in the precedingvehicle and/or the closing of the throttle valve of the precedingvehicle.

As explained in more detail below, the vehicle on-board unit 12 isconfigured and arranged to communicate with other vehicle and theroadside units 16 to send and receive vehicle parameters relating tosafety issues including but not limited to, a path history with a centerlane offset to increase the accuracy of a lane centerline determinationof the road that the host vehicle is traveling, a current vehicleposition to activate the anti-tailgating feature, and throttleinformation to activate the potential braking alert feature.

Still referring to FIG. 2, the control unit 20 is operatively connectedto the two-way wireless communication system 21, the human-machineinterface section 22, the global positioning system 23, the map databaseand storage section 25, the steering vibrating device 28, the throttlevalve opening sensor 34, and the visual warning indicator 36. Thecontrol programs of the control unit 20 is programmed to includefunctions that can be generally divided into a navigation controlcomponent, a common message set processing component, a lane centerlinedetermining component, a vehicle traveling condition detecting componentand a safety response determining component. The navigation controlcomponent is configured to control the navigation functions of thenavigation unit. The navigation functions are conventional, and thus,the navigation functions will not be discussed herein.

The common message set processing component is configured to the processthe signals from the various vehicle sensors to produce the outgoingcommon message set, and to process the incoming common message sets fromother vehicles 10 and/or roadside units 16. In particular, the two-waywireless communication system 21 is operatively connected to the commonmessage set processing component to provide the incoming messages fromneighboring vehicle to common message set processing component of thecontrol unit 20. Thus, the common message set processing componentbasically includes a vehicle path history generating section, anincoming message receiving section, an incoming message relevancysection and a relevancy adjustment section. The vehicle path historygenerating section generates a host vehicle path history data indicativeof a travel path of the host vehicle based on the signals from theglobal positioning system 23. The incoming message receiving sectionreceives incoming common message sets at least containing vehicle pathhistory data of neighboring (preceding and following) vehicles withstatistical information and throttle release data of neighboring(preceding and following) vehicles from the two-way wirelesscommunication system 21. The incoming message relevancy section isconfigured to perform a relevancy determination of the throttle releasedata received by the incoming message receiving section. The relevancyadjustment section is configured to adjust the relevancy determinationof the throttle release data to selectively change when the driver ofthe host vehicle is alerted of the potential braking situation of thepreceding vehicle based on the vehicle traveling condition determined bythe vehicle traveling condition detecting component.

The lane centerline determining component is configured to process thedata of the common message set processing component to more accuratelydetermine the lane centerline of the lane that the host vehicle istraveling. In particular, the lane centerline determining component isconfigured to determine a lane centerline of the lane that the hostvehicle is currently traveling based on the host vehicle path historydata that is generated by the vehicle path history generating section,and the preceding vehicle path history data that is received by theincoming message receiving section and processed by the incoming messagerelevancy section and the relevancy adjustment section as explainedbelow.

The vehicle traveling condition detecting component is configured toprocess the various signals relating to the current traveling conditionof the host vehicle and/or neighboring vehicles. The vehicle travelingcondition detecting component of the control unit 20 receives varioussignals from the vehicle sensors that indicate a current vehicletraveling condition of the host vehicle. Thus, the vehicle travelingcondition detecting component of the control unit 20 function as avehicle traveling condition detecting section that determines a currentvehicle traveling condition of the host vehicle. When the control unit20 is performing the anti-tailgating feature, the vehicle travelingcondition detecting component of the control unit 20 more specificallyfunction as a host vehicle safety zone detecting section that isconfigured to detect a vehicle traveling condition indicative of apotentially inadequate safety zone occurring in the host vehicle.

The safety response determining component is configured to activate thevarious warning devices and/or countermeasure devices upon detecting apotential safety concern to the host vehicle. Thus, the safety responsedetermining component includes an automatic brake light triggeringsection, a brake light activating section and a driver warning section.The automatic brake light triggering section and the brake lightactivating section are used in connection with the anti-tailgatingfeature of the present invention, while the driver warning section isused in connection with the potential braking alert feature of thepresent invention. The driver warning section is configured toselectively alert a driver of the host vehicle of a potential brakingsituation of the preceding vehicle based upon the relevancydetermination of the incoming message relevancy section. The safetyresponse determining component of the control unit 20 performs the dualfunctions of an automatic brake light triggering section and a brakelight activating section. The automatic brake light triggering sectionis configured to output a brake light activation signal upon determininga predetermined condition has been satisfied based upon the vehicletraveling condition detected by the vehicle traveling conditiondetecting section.

As seen in FIG. 3, the two-way wireless communications are conductedbetween the vehicles 10 as well as between the vehicles 10 and theroadside units 16. The external server 18 is configured and arranged tocommunicate with the vehicle on-board unit 12 to provide the off-boardnavigation service through wireless communications via the roadsideunits 16 within the two-way wireless communications network, if needand/or desired. In particular, the roadside units 16 (only two shown)relays signals between the vehicle on-board units 12 of the hostvehicles 10 and the external server 18. Thus, the roadside units 16 areconfigured to send signals to the external server 18 and the vehicleon-board units 12 of the host vehicles 10, and receive signals from thevehicle on-board units 12 of the host vehicles 10 and the externalserver 18. While the two-way wireless communications network isillustrated as a dedicated short range communications (DSRC) network, itwill be apparent to those skilled in the art from this disclosure thatother types of two-way wireless communications networks can be used tocarry out the present invention. For example, it will be apparent tothose skilled in the art from this disclosure that two-waycommunications such as cellular, Wimax, Wifi, etc can be used as atwo-way wireless communications network to carry out the presentinvention.

The global positioning satellite 14 is a conventional component that isknown in the art. Since the global positioning satellite is known in theart, the structures of the global positioning satellite 14 will not bediscussed or illustrated in detail herein. Rather, it will be apparentto those skilled in the art from this disclosure that the globalpositioning satellite 14 can be any type of structure that can be usedto carry out the present invention.

The host vehicles 10 are preferably each equipped with a vehicle traveldata collection unit so that information can be communicated between thevehicles 10 and the nearby roadside units 16 within the two-way wirelesscommunications network. More specifically, each of the roadside units 16is equipped with a DSRC unit or other suitable two-way wirelesscommunication system for broadcasting and receiving signals to/from thehost vehicles 10 located within a prescribed communication(broadcasting/receiving) region surrounding the roadside unit 16.Moreover, each roadside unit 16 is preferably an IP enabledinfrastructure that is configured and arranged to establish a linkbetween the vehicle on-board unit 12 of the host vehicle 10 and anexternal service provider, such as the external server 18. Specifically,in the present invention, the roadside unit 16 is configured andarranged to establish a link between the vehicle on-board units 12 ofthe host vehicles 10 and the external server 18. An example is shown inFIG. 3 in which the vehicle on-board unit 12 of the host vehicle 10establishes a link to the external server 18 via the roadside unit 16 inclose proximity to the host vehicle 10. The external server 18 is, forexample, a telecommunications provider or a service provider such as thevehicle's manufacturer. Since roadside units are known in the art, thestructures of the roadside units 16 will not be discussed or illustratedin detail herein. Rather, it will be apparent to those skilled in theart from this disclosure that the roadside unit can be any type ofstructure that can be used to carry out the present invention.

The control unit 20 preferably includes a microcomputer with a lanecenterline determining program and vehicle safety response programsincluding an anti-tailgating program and a potential braking situationalert program. The lane centerline determining program is especiallyuseful in assisting in the relevancy determination of incoming messagesfrom other vehicles. Thus, determining an accurate lane centerline, thehost vehicle can determine if a message from a following vehicle isrelevant such that the anti-tailgating program activates the hostvehicle brake lights 38 or a message from a preceding vehicle isrelevant such that the potential braking situation alert programactivates a warning signal to the driver of the potential brakingsituation.

Basically, in the lane centerline determining program discussed below,the accuracy of determining a centerline of lane is accomplished bycumulating path histories of vehicles and integrating this path historyinformation to obtain a cumulative lane centerline for a lane of a road.In other words, the vehicle path histories are from several vehicles areused together to develop an accurate lane centerline. For example, afirst vehicle broadcasts first vehicle path history data indicative of atravel path of the first vehicle that has traveled along a vehicle lane.Then, a second vehicle subsequently traveling the lane will receive thefirst vehicle path history data and broadcast cumulative vehicle pathhistory data using its own (second) vehicle path history data and thefirst vehicle path history data to indicate the centerline of the lane.Next, a third vehicle subsequently traveling the lane will receive thecumulative vehicle path history data path history from the secondvehicle, and will revise the position of centerline of the lane based onthe third vehicle path history data and the cumulative vehicle pathhistory data. This lane centerline data will be continuously transmittedto each subsequent vehicle to develop very accurate lane centerlinedata.

Basically, in the anti-tailgating program discussed below, the vehicletraveling condition detecting section of the control unit 20 ispreferably configured to detect one or more factors that affect theappropriate following distance. Upon the vehicle traveling conditiondetecting section of the control unit 20 determining a predeterminedcondition has been satisfied based upon the vehicle traveling conditionsthat were detected, the automatic brake light triggering section of thecontrol unit 20 outputs a brake light activation signal to the brakelight activating section of the control unit 20. When the brake lightactivation signal from the automatic brake light triggering section ofthe control unit 20 is received by the brake light activating section ofthe control unit 20, then the brake light activating section of thecontrol unit 20 activates the brake lights 38 so that that flash at thefollowing vehicle. The brake lights 38 will continue to be flashed atthe following vehicle until the potentially inadequate safety zoneoccurring in a host vehicle ceases to exist. The brake light activatingsection of the control unit 20 activates the brake lights 38 of the hostvehicle without a braking operation being performed in the host vehicleupon receiving the brake light activation signal from automatic brakelight triggering section of the control unit 20.

Basically, in the potential braking situation alert program discussedbelow, the incoming message receiving section of the control unit 20receives a preceding vehicle message containing throttle release data ofthe preceding vehicle located in front of the host vehicle. Then, theincoming message relevancy section of the control unit 20 performs arelevancy determination of the throttle release data that was receivedby the host vehicle, and the driver warning section of the control unit20 selectively alert the driver of the host vehicle of a potentialbraking situation of the preceding vehicle based upon the relevancydetermination of the throttle release data.

The control unit 20 also preferably includes other conventionalcomponents such as an input interface circuit, an output interfacecircuit, and storage devices such as a ROM (Read Only Memory) device anda RAM (Random Access Memory) device. The memory circuit storesprocessing results and control programs such as ones for operation ofthe two-way wireless communication system 21, the human-machineinterface section 22, the global positioning system 23, the map databaseand storage section 25, the steering vibrating device 28, the throttlevalve opening sensor 34, and the visual warning indicator 36. Thecontrol unit 20 is capable of selectively controlling other DSRCcomponents of the host vehicle 10 such as other safety systems as neededand/or desired. It will be apparent to those skilled in the art fromthis disclosure that the precise structure and algorithms for thecontrol unit 20 can be any combination of hardware and software thatwill carry out the functions of the present invention.

The two-way wireless communication system 21 preferably includescommunication interface circuitry that connects and exchangesinformation with other ones of the vehicles 10 that are similarlyequipped as well as with the roadside units 16 through a wirelessnetwork within the broadcast range of the host vehicle 10. The two-waywireless communication system 21 is preferably configured and arrangedto conduct direct two-way communications between vehicles(vehicle-to-vehicle communications) and roadside units(roadside-to-vehicle communications). Moreover, the two-way wirelesscommunication system 21 is preferably configured to periodicallybroadcast a signal with the so called common message set in thebroadcast area. The so called common message set can be broadcasted inthree different way, i.e., (1) event based broadcasting, (2) periodicbroadcasting and (3) hybrid (event based/periodic) broadcasting.Preferably, periodic broadcasting or hybrid (event based/periodic)broadcasting is used to carry out the present invention. Thus, thetwo-way wireless communication system 21 acts as a two-way wirelesscommunications section that is configured to receive the incoming commonmessage sets from neighboring (preceding and following) vehicles. Inconnection with the present invention, the incoming common message setat least includes vehicle path history data with statisticalinformation, lane boundaries and throttle release data. Also, thetwo-way wireless communication system 21 is configured to broadcast thecommon message set of the host vehicle. The broadcasted common messageset preferably at least includes the host vehicle path history data andthe preceding vehicle path history data (i.e., cumulative vehicle pathhistory). Preferably, the two-way wireless communications system 21 isfurther configured to broadcast a degree of uncertainty associated withthe cumulative vehicle path history and the lane boundaries of the hostvehicle as a part of the common message set for the host vehicle.

More specifically, as seen in FIG. 2, the two-way wireless communicationsystem 21 is an on-board unit that includes a host vehicle two waycommunication device 21A and one or more antennas 21B. As mentionedabove, the two-way wireless communication system 21 can be any suitabletwo-way wireless system, e.g., DSRC cellular, Wimax, Wifi, etc. The twoway communication device 21A is configured to at least conduct directshort range communications in a host vehicle broadcast area surroundingthe host vehicle 10 via the antennas 21B. Preferably, the antennas 21Binclude both an omni-directional antenna and a multi-directionalantenna. In one preferred embodiment, the two-way wireless communicationsystem 21 is a dedicated short range communication (DSRC) system, sincethe latency time between communications is very low compared to mostother technologies that are currently available. However, other two-waywireless communication systems can be used if they are capable ofconducting both point-to-point wireless communications and broadcastwireless messages in a limited broadcast area so long as the latencytime between communications is short enough to carry out the presentinvention. When the two-way wireless communication system 21 is a DSRCsystem, the two-way wireless communication system 21 will transmit at a75 Mhz spectrum in a 5.9 GHz band with a data rate of 1 to 27 Mbps, anda maximum range of about 1,000 meters. Preferably, the two-way wirelesscommunication system 21 includes seven (7) non-overlapping channels. Thetwo-way wireless communication system 21 will be assigned a MediumAccess Control (MAC) address and/or an IP address so that each vehiclein the network can be individually identified.

The global positioning system 23 is a conventional global positioningsystem (GPS) that is configured and arranged to receive globalpositioning information of the host vehicle 10 in a conventional manner.Basically, the GPS unit 23A is a receiver for receiving a signal fromthe global positioning satellite 14 (FIG. 1) via the GPS antenna 23B.The signal transmitted from the global positioning satellite 14 isreceived at regular intervals (e.g. one second) to detect the presentposition of the host vehicle 10. The GPS unit 23A preferably has anaccuracy of indicting the actual vehicle position within a few meters orless. This data (present position of the host vehicle) is fed to thecontrol unit 20 for processing. Moreover, the GPS data is alsotransmitted to the roadside units 16 through wireless communications forthe off-board navigation processing.

The roadside units 16 are configured to obtain positions of the hostvehicles 10 that are traveling along various routes. The two-waywireless communication system 21 of host vehicles 10 communicates withthe roadside units 16 along the travel route. The roadside units 16 arepositioned at various distances along different routes.

Basically, the increased accuracy in determining the centerline of laneis accomplished by cumulating path histories of vehicles and integratingthis path history information to obtain a cumulative lane center for alane of a road. More specifically, for example, the two-way wirelesscommunication system 21 of each of the vehicles 10 periodicallybroadcasts a signal with a so called common message set in the broadcastarea. This common message set includes a path history (i.e.,breadcrumbs) that is formed by a plurality of GPS points. Thus, apreceding or lead vehicle (vehicle #1) broadcasts its path history,which is indicative of the centerline of the lane that it is traveling.A following vehicle (vehicle #2) receives the path history of thevehicle #1, and then calculates the centerline of the lane that it istraveling based on both its own path history and the path history of thevehicle #1. Then, another following vehicle (vehicle #3) receives thepath history of the vehicle #2 and a cumulative lane center offset aswell as other statistical information discussed below. The vehicle #3now calculates the centerline of the lane that it is traveling based onboth its own path history and the cumulative lane center offsetbroadcasted by the vehicle #2. The vehicle #3 will now broadcast its ownpath history and an amended cumulative lane center offset that is basedon the path histories of vehicles #1, #2 and #3. In other words, theamended cumulative lane center offset broadcasted by the vehicle #3includes slight adjusts the prior cumulative lane center offsetbroadcasted by the vehicle #2 based on its integrated information. Thus,the cumulative lane center offset becomes increasingly more accurateover time with each of the vehicles adding its own path history.Integration of the broadcasting vehicle's information could happen in avariety of manners. One potential method of integrating the pathhistories of vehicles to develop an accurate center of a lane caninclude the following embodiment.

The lead vehicle #1 communicates its path history (i.e., breadcrumbs) asa plurality of GPS points V1(1), V1(2), V1(3), V1(4), V1(5), V1(6),V1(7), V1(8), V1(9), V1(10), etc. Then, the following vehicle #2integrates its path history (i.e., breadcrumbs) with the path history(i.e., breadcrumbs) of the lead vehicle #1 to obtain an offset value foreach GPS point. For example, the following vehicle #2 has a path history(i.e., breadcrumbs) with the GPS points V2(1), V2(2), V2(3), V2(4),V2(5), V2(6), V2(7), V2(8), V2(9), V2(10), etc. and calculates laneoffset values O3(1), O3(2), O3(3), O3(4), O3(5), O3(6), O3(7), O3(8),O3(9), O3(10), etc. The control unit 20 of the following vehicle #2calculates the lane offset value O2(1) for GPS points V1(1) and V2(1)using, for example, the following equation: O2(1)=α(V1(1))+β(V2(1)).Preferably, in this example, α equals a fractional constant value thatheavily weights previously known information, while β equals afractional constant value that underweights the its own vehicleinformation. The other offset values are calculated in the same manner.Thus, the following vehicle #2 communicates its path history (i.e.,breadcrumbs) with the GPS points V2(1), V2(2), V2(3), V2(4), V2(5),V2(6), V2(7), V2(8), V2(9), V2(10), etc. and the calculated center laneoffset values O2(1), O2(2), O2(3), O2(4), O2(5), O2(6), O2(7), O2(8),O2(9), O2(10), etc. Now, when the subsequently following vehicle #3receives the broadcast of the path history and the center lane offsetfrom the following vehicle #2, the control unit 20 of the subsequentlyfollowing vehicle #3 integrates its path history (i.e., breadcrumbs)with the path history (i.e., breadcrumbs) of the following vehicle #2 toobtain an amended offset value for each GPS point. In other words, thesubsequently following vehicle #3 has a path history (i.e., breadcrumbs)with the GPS points V3(1), V3(2), V3(3), V3(4), V3(5), V3(6), V3(7),V3(8), V3(9), V3(10), etc. and calculates the amended lane offset valuesO3(1), O3(2), O3(3), O3(4), O3(5), O3(6), O3(7), O3(8), O3(9), O3(10),etc. The subsequently following vehicle #3 basically uses the sameequation that was used by the following vehicle #2 to calculate theamended offset values, except now the offset values calculated by thefollowing vehicle #2 are used instead of the GPS points of the leadvehicle #1. Namely, the subsequently following vehicle #3 calculates alane offset value O3(1) for GPS point V3(1) using for example thefollowing equation: O3(1)=α(O2(1))+β(V2(1)). Preferably, α equals afractional constant value that heavily weights previously knowninformation, while β equals a fractional constant value thatunderweights the its own vehicle information. The other offset valuesfor the GPS points of subsequently following vehicle #3 are calculatedin the same manner. Thus, the lane centerline determining component ofthe control unit 20 is configured to weight the preceding vehicle pathhistory data more heavily than the host vehicle path history data indetermining the centerline of the lane. In other words, the lanecenterline determining component is further configured to increase aweight given to the preceding vehicle path history data in determiningthe centerline of the lane as the statistical information includes morevehicle path histories.

Preferably, the lane offset values that are broadcasted includestatistical indictor that indicates the number of vehicle path historiesincluded in the lane offset values as well as other statisticalinformation including a mean value and a standard deviation for the laneoffset values. This would permit the following vehicle to integrate thefollowing vehicle information as one of a known number of vehiclesinstead of a blind integration. Moreover, this would provide morestatistical information about lane positioning. Also, each of thevehicles could communicate its lane boundaries for the GPS points thathad previously been communicated within the lane to thereby provide avirtual zone of relevance. Furthermore, each of the vehicles couldcommunicate the uncertainty associated with the lane offset values fordetermining the cumulative centerline of the lane. For example, if thelane offset values are based upon a single vehicle with inaccuratepositioning information, the uncertainty may be very high. However,during accumulation of path histories, lane offset values might increasethe degree of certainty and provide a degree of uncertainty indicatorwith the path history data to following vehicles. Thus, thedetermination of the centerline of the lane can be adjusted insubsequent or following vehicles using the statistical informationrelating to the preceding vehicle path histories and/or using laneboundary data for the GPS points, and/or using a degree of uncertaintyindicator associated with the cumulative vehicle path history data.

Referring now to a flowchart of FIG. 5, a simplified flow chart isillustrated to explain the basic functions that are performed in thevehicle on-board unit 12 when conducting the lane centerlinedetermination in accordance with one embodiment of the presentinvention. Of course, it will be apparent to those skilled in the artfrom this disclosure that other options, can be provided to the user inaddition to the ones described and illustrated in the embodiment beingused to illustrate the basic functions of the present invention.

When the user first turns on the vehicle, the vehicle on-board unit 12is activated. The control unit 20 then obtains the current location ofthe host vehicle 10 via the global positioning system 23 (step S1). TheGPS data (current location) of the host vehicle is used by the vehiclepath history generating section of the control unit 20 to generate acurrent host vehicle path history (PH) that comprises a plurality of GPSpoints which are diagrammatically illustrated in FIG. 6 as breadcrumbs.This host vehicle path history is associated with the map information todetermine a lane centerline for the road that the host vehicle istraveling. In certain safety applications such as the potential brakingalert feature of the present invention, it is desirable to accuratelydetermine the lane of the preceding vehicle in which the potentialbraking situation may be occurring.

Prior to receiving a relevant incoming, as discussed below, the controlunit 20 initially generates first vehicle path history data (the clearcircles in FIG. 6) indicative of a travel path of a first vehicle V#1(FIG. 6) that has traveled along a vehicle lane. The first vehicle V#1will use this first vehicle path history data and its map information indetermining its position on the road and the centerline of the lane ifno other vehicle path history data is available. As seen in FIG. 6, thebreadcrumbs (the clear circles in FIG. 6) of the vehicles are not alwayson the centerline indicated by the dashed and dotted line.

Immediately after the vehicle on-board unit 12 has been activated, thetwo-way wireless communication system 21 starts listening for incomingmessages. In particular, the control unit 20 processes the incomingmessages received by the two-way wireless communication system 21 fromother vehicles 10 and the roadside units 16 that are within thecommunication area. In step S2, the control unit 20 determines if any ofthe incoming messages are relevant to the lane that the host vehicle istraveling. In other words, the control unit 20 selects the incomingmessages from preceding vehicles that are traveling ahead of the hostvehicle and that are traveling in the same lane as the host vehicle.Thus, the host vehicle receives the vehicle path history data from oneor more preceding vehicles that previously traveled the same vehiclelane the host vehicle is currently traveling.

In the event that one of the incoming messages is relevant, i.e.,contains a relevant path history message, then the control unit 20recalculates the lane centerline of the host vehicle 10 with thecumulative lane centerline data of the path history message from theincoming messages (step S3). In other words, the host vehicle now usesit own vehicle path history data that is indicative of a travel path ofthe host vehicle along the vehicle lane and the prior vehicle pathhistory data that is indicative of a travel path of one or morepreceding vehicles that have traveled along the vehicle lane indetermining an amended centerline of the lane. Preferably, in step S3,the lane centerline determining component of the control unit isconfigured to weight the preceding vehicle path history data moreheavily than the host vehicle path history data in determining thecenterline of the lane. In other words, the lane centerline determiningcomponent is further configured to increase a weight given to thepreceding vehicle path history data in determining the centerline of thelane as the statistical information includes more vehicle path historiesas discussed above.

As seen in FIG. 6, the second vehicle V#2 receives the vehicle pathhistory from the first vehicle #1 and calculates the center lane offsetsby the black circles in FIG. 6. Preferably, in updating the vehicle pathhistory to determine an amended centerline of the lane, the control unit20 of the host vehicle is configured to more heavily weighting precedingvehicle path history data than its own vehicle path history data indetermining the centerline of the lane as discussed above.

Next, in step S4, the two-way wireless communication system 21 of thehost vehicle broadcast its common message set with its amended pathhistory message and other vehicle parameters as mentioned above. Whenthe process has proceeded directly from step S3 to step S4, then theamended path history message is an amended cumulative vehicle pathhistory.

In step S2, if there are no incoming messages that are relevant to thecalculation of the lane centerline of the lane that the host vehicle istraveling, then the process proceeds to step S4 where the control unit20 of the host vehicle 10 broadcast its common message set with itsrecalculated path history message based on the current information thatits available. In other words, regardless of the relevancy of theincoming message, the host vehicle would calculate the lane centerlineand broadcast the Common Message Set with its known lane centerlineinformation. In this way, the host vehicle periodically broadcasts itspath history message based on its own path history and/or in conjunctionwith other preceding vehicles path history.

Turning now to the anti-tailgating feature of the present invention.Here, the control unit 20 is configured to activate the brake lights 38of the host vehicle without performing a braking operation in the hostvehicle when the control unit 20 determines that the current travelingconditions are such that the following vehicle is traveling too close tothe host vehicle. More specifically, the vehicle traveling conditiondetecting section of the control unit 20 is preferably configured todetect one or more factors that affect the appropriate followingdistance. In the illustrated embodiment, the vehicle traveling conditiondetecting section of the control unit 20 preferably detects a hostvehicle location (local road, highway, school zone, etc.) using theglobal positioning system 23 together with map information received fromthe map database and storage section or the external server 18 as partof the vehicle traveling conditions that are indicative of thepotentially inadequate safety zone existing between the host vehicle andthe following vehicle. Also in the illustrated embodiment, the vehicletraveling condition detecting section of the control unit 20 preferablydetects a host vehicle speed as part of the vehicle traveling conditionsthat are indicative of the potentially inadequate safety zone existingusing a vehicle speed sensor (one of the in-vehicle sensors shown inFIG. 2). Further in the illustrated embodiment, the vehicle travelingcondition detecting section of the control unit 20 preferably detects afollowing distance between the host vehicle and a following vehicle aspart of the vehicle traveling conditions that are indicative of thepotentially inadequate safety zone existing using a laser range finder,a camera or information from the incoming common message set from thefollowing vehicle. In addition, the vehicle traveling conditiondetecting section of the control unit 20 can also detect a relativespeed between the host vehicle and the following vehicle as part of thevehicle traveling condition that is indicative of the potentiallyinadequate safety zone using a laser range finder, a camera orinformation from the incoming common message set from the followingvehicle. Moreover, the vehicle traveling condition detecting section ofthe control unit 20 can also detect an amount of throttle release in thehost vehicle as part of the vehicle traveling condition that isindicative of the potentially inadequate safety zone existing using thethrottle valve opening sensor 34. The vehicle traveling conditiondetecting section can also be configured to detect drivingcharacteristics of the host vehicle over a prescribed period of time aspart of the vehicle traveling condition that is indicative of thepotentially inadequate safety zone existing using the in vehicle sensorsshown in FIG. 2 to develop the driving characteristics of the hostvehicle. Each of these traveling conditions as well as other travelingconditions (not mentioned) affecting a safe following distance can beused individually or in any combination to develop a prescribed triggeror set point for outputting a brake light activation signal. Also asexplained below, when one or more of these traveling conditions are usedtogether to develop a prescribed trigger or set point, the prescribedtrigger or set point can change as one of the traveling conditionschanges. In other words, these traveling conditions are interdependentsuch that as one condition changes, another condition may need to beadjusted in order to attempt to obtain appropriate safety zone orfollowing distance.

Based on one or more of these traveling conditions (e.g., the hostvehicle location, the host vehicle speed, the following distance of thefollowing vehicle, the relative speed between the vehicles, the throttlerelease amount and/or the host vehicle driving characteristics), theautomatic brake light triggering section of the control unit 20determines whether or not selected prescribed vehicle travelingconditions exist that are indicative of a potentially inadequate safetyzone existing between the host vehicle and the following vehicle. Theautomatic brake light triggering section of the control unit 20 can alsooptionally adjust the trigger or point for determining when to outputthe brake light activation signal depending on such factors affectingthe appropriate following distance such as the host vehicle location,the host vehicle speed, the following distance of the following vehicle,the relative speed between the vehicles, the throttle release amountand/or the host vehicle driving characteristics. Stated differently, theautomatic brake light triggering section adjusts the predeterminedtriggering conditions that must be met in order to determine when tooutput the brake light activation signal as the traveling conditionschange. For example, as the host vehicle speed increases, the followingdistance of the following vehicle should increase. Thus, as the hostvehicle speed increases, the trigger or set point of the automatic brakelight triggering section of the control unit 20 is set to activate thebrake lights 38 sooner, i.e., the acceptable following distance of thefollowing vehicle is increased. This could be accomplished by using aprestored control map plotting in the trigger point which the followingdistance is set on one axis of the control map and the vehicle speed isset on the other axis of the control map.

In the case of the throttle release amount, the automatic brake lighttriggering section can use a rate of change in the amount of throttlerelease between two throttle positions as part of the predeterminedcondition used to determine when to output the brake light activationsignal. The trigger or set point for outputting a brake light activationsignal based on the throttle release amount in the host vehicle ispreferably adjusted depending on one or more of the traveling conditions(e.g., the host vehicle location, the host vehicle speed, the followingdistance of the following vehicle, the relative speed between thevehicles and/or the host vehicle driving characteristics).Alternatively, the automatic brake light triggering section uses a dropin an amount of throttle release to a closed throttle position within aprescribed period of time as part of the predetermined condition used todetermine when to output the brake light activation signal. Again thetrigger or set point for outputting a brake light activation signal canbe depending on one or more of the traveling conditions. Of course, thetrigger or set point could be a fixed prescribed throttle release amountthat not adjusted when the other traveling conditions are changed ifneeded and/or desired.

In any event, upon the vehicle traveling condition detecting section ofthe control unit 20 determining a predetermined condition has beensatisfied based upon the vehicle traveling conditions that weredetected, the automatic brake light triggering section of the controlunit 20 outputs a brake light activation signal to the brake lightactivating section of the control unit 20. When the brake lightactivation signal from the automatic brake light triggering section ofthe control unit 20 is received by the brake light activating section ofthe control unit 20, then the brake light activating section of thecontrol unit 20 activates the brake lights 38 so that that flash at thefollowing vehicle. The brake lights 38 will continue to be flashed atthe following vehicle until the potentially inadequate safety zoneoccurring in a host vehicle ceases to exist. The brake light activatingsection of the control unit 20 activates the brake lights 38 of the hostvehicle without a braking operation being performed in the host vehicleupon receiving the brake light activation signal from automatic brakelight triggering section of the control unit 20.

Referring now to a flowchart of FIG. 7, a simplified flow chart isillustrated to explain the basic functions that are performed in thevehicle on-board unit 12 when conducting the anti-tailgating method toactivate brake lights 38 in the host vehicle upon determining a vehicletraveling condition exists that is indicative of a potentiallyinadequate safety zone between the host vehicle and a following vehicle.Of course, it will be apparent to those skilled in the art from thisdisclosure that other options, can be provided in addition to the onesdescribed and illustrated in the embodiment that is being used toillustrate the basic functions of the present invention.

As mentioned above, immediately after the vehicle on-board unit 12 hasbeen activated, the two-way wireless communication system 21 startslistening for incoming messages from other vehicles 10 and the roadsideunits 16 that are within the communication area. Also immediately afterthe vehicle on-board unit 12 has been activated, in step S11, thetwo-way wireless communication system 21 starts broadcasting its commonmessage set with its path history message and other vehicle parametersas mentioned above.

Next in step S12, the control unit 20 processes the incoming messagesreceived by the two-way wireless communication system 21 from othervehicles 10 and/or the roadside units 16 that are within thecommunication area. In other words, in step S12, the control unit 20determines if any of the incoming messages are relevant to the lane thatthe host vehicle is traveling and if any of the incoming messages arefrom a following vehicle. If one of the incoming messages is from afollowing vehicle that is in the same lane as the host vehicle, thenthat incoming message is relevant to the anti-tailgating feature of thepresent invention.

Next the process proceeds to step S13, where the control unit 20determines if a safe following distance exists between the host vehicleand the following vehicle. This determination is performed based on oneor more vehicle traveling conditions of the host vehicle and/or one ormore vehicle traveling conditions of the following vehicle. In otherwords, the control unit 20 determines whether a vehicle travelingcondition exists that is indicative of a potentially inadequate safetyzone occurring in the host vehicle equipped with the vehicle on-boardunit 12. Thus, the control unit 20 determines if the following vehicleis too close to the host vehicle by considering the current travelingconditions of the host vehicle and/or the following vehicle as mentionedabove.

If the control unit 20 determines that a safe following distance exists,then the process proceeds back to step S11, where the cycle will berepeated. However, if the control unit 20 determines that a safefollowing distance does not exist, then the process proceeds to step S14where the control unit 20 actives the brake lights 38. In other words,the control unit 20 determines that the following vehicle is too closeand the brake lights 38 will flash to move the following vehicle off thetail end of the host vehicle.

Turning now to the potential braking alert feature of the presentinvention. Here, the control unit 20 is configured to alert the driverof the host vehicle when the control unit 20 determines that the currenttraveling conditions are such that a potential braking situation existsin a preceding vehicle is traveling in the same lane as the hostvehicle. More specifically, in the potential braking alert feature, theincoming message receiving section of the control unit 20 receive apreceding vehicle common message set containing throttle release data ofa preceding vehicle located in front of the host vehicle. The incomingmessage relevancy section of the control unit 20 performs a relevancydetermination of the throttle release data received by the incomingmessage receiving section of the control unit 20. The driver warningsection of the control unit 20 then selectively alert a driver of thehost vehicle of a potential braking situation of the preceding vehiclebased upon the relevancy determination of the incoming message relevancysection of the control unit 20. For example, the incoming messagerelevancy section of the control unit 20 can perform the relevancydetermination of the throttle release data either based on an amount ofthrottle release, or based on a rate of change in the amount of throttlerelease between two throttle positions. Alternatively, the incomingmessage relevancy section of the control unit 20 can perform therelevancy determination of the throttle release data based on a drop inthe amount of throttle release to a closed throttle position within aprescribed period of time.

Preferably, the driver warning section of the control unit 20 is furtherconfigured to produce a first warning signal to alert the driver of thepotential braking situation based upon the relevancy determinationsatisfying a first condition indicative of a slow throttle releasingaction in the preceding vehicle, and to produce a second warning signalto alert the driver of the potential braking situation based upon therelevancy determination satisfying a second condition indicative of afast throttle releasing action in the preceding vehicle with the firstand second warning signals being different. In the illustratedembodiment, the driver warning section of the control unit 20 is furtherconfigured to produce a first visual signal using the visual warningindictor 26 to project a yellow brake warning signal on the windshield(see FIG. 4) of the vehicle as part of the first warning signal.Moreover, in the illustrated embodiment, the driver warning section ofthe control unit 20 is further configured to produce a second visualsignal using the visual warning indictor 26 to project a red brakewarning signal on the windshield (see FIG. 4) of the vehicle as part ofthe second warning signal. Of course, other visual indicators could beused such as a bar graph. Also, in the illustrated embodiment, thedriver warning section of the control unit 20 is further configured toproduce an audible signal using the audio speaker 22B as part of thesecond warning signal in addition to the second visual signal producedby the visual warning indictor 26. Alternatively, a haptic warningsignal can be used in addition to or instead of the first and secondvisual warnings to alert the driver of the potential braking situation.For example, the steering vibrating device 28 can vibrate the steeringwheel of the steering structure 26 when the control unit 20 determinesthat it is desirable to warn the driver of a safety concern such as apotential braking situation occurring in the preceding vehicle as partof either the first or second warning signals. In other words, anycombination of visual warnings, auditory warnings and haptic warningscan be to produce two or more distinct warnings to alert the driver ofthe level of the potential braking situation. Preferably, as thepotential braking situation increases in risk, the stimuli to the driverincrease. Thus, for example, a low warning level could only use a visualwarning, a medium warning level could use both visual and auditorywarnings, and a high warning level could use visual, auditory and hapticwarnings.

Preferably, the potential braking alert feature of the present inventionalso uses the vehicle traveling condition detecting section to detect avehicle traveling condition relating to a potential braking situationoccurring in the preceding vehicle. More specifically, the vehicletraveling condition detecting section of the control unit 20 is furtherpreferably configured to detect one or more factors that affect thepotential risk of a braking situation occurring in the precedingvehicle. In the illustrated embodiment, as mentioned above, the vehicletraveling condition detecting section of the control unit 20 preferablydetects among other things, the host vehicle location (local road,highway, school zone, etc.) the host vehicle speed, an amount ofthrottle release in the host vehicle, and driving characteristics of thehost vehicle over a prescribed period of time. Moreover, the vehicletraveling condition detecting section of the control unit 20 alsopreferably detects a host following distance between the host vehicleand a preceding vehicle using a laser range finder, a camera orinformation from the incoming common message set from the precedingvehicle, and a relative speed between the host vehicle and the precedingvehicle using a laser range finder, a camera or information from theincoming common message set from the preceding vehicle. Each of thesetraveling conditions as well as other traveling conditions (notmentioned) affecting a safe following distance can be used individuallyor in any combination to develop a prescribed trigger or set point foroutputting a producing warning signals. Also as explained below, whenone or more of these traveling conditions are used together to develop aprescribed trigger or set point, the prescribed trigger or set point canchange as one of the traveling conditions changes. In other words, thesetraveling conditions are interdependent such that as one conditionchanges, another condition may need to be adjusted in order to warn thedriver of a potential braking situation existing that is relevant to thehost vehicle. For example, the vehicle traveling condition detectingsection detects a following distance between the host vehicle and thepreceding vehicle as part of the vehicle traveling condition as well asa host vehicle speed as part of the vehicle traveling condition. Thevehicle traveling condition detecting component can further detect arelative speed between the host vehicle and the preceding vehicle aspart of the vehicle traveling condition.

Referring now to a flowchart of FIG. 8, a simplified flow chart isillustrated to explain the basic functions that are performed in thevehicle on-board unit 12 when conducting the potential braking situationalert method to alert the driver of a potential braking situation in apreceding vehicle. Of course, it will be apparent to those skilled inthe art from this disclosure that other options, can be provided inaddition to the ones described and illustrated in the embodiment that isbeing used to illustrate the basic functions of the present invention.

As mentioned above, immediately after the vehicle on-board unit 12 hasbeen activated, the two-way wireless communication system 21 startslistening for incoming messages from other vehicles 10 and the roadsideunits 16 that are within the communication area. Also immediately afterthe vehicle on-board unit 12 has been activated, in step S21, thetwo-way wireless communication system 21 starts broadcasting its commonmessage set with its path history message and other vehicle parametersas mentioned above.

Next in step S22, the control unit 20 processes the incoming messagesreceived by the two-way wireless communication system 21 from othervehicles 10 and/or the roadside units 16 that are within thecommunication area. In other words, in step S22, the control unit 20determines if any of the incoming messages are relevant to the lane thatthe host vehicle is traveling and if any of the incoming messages arefrom a preceding vehicle. If one of the incoming messages is from apreceding vehicle that is in the same lane as the host vehicle, thenthat incoming message is relevant to the potential braking alert featureof the present invention.

Next the process proceeds to step S33, where the control unit 20determines if the incoming message of the preceding vehicle containsthrottle releasing data (accelerator pedal releasing or throttle valveopening closing) is indicative of a potential braking situation in thepreceding vehicle. If the control unit 20 determines the incomingmessage of the preceding vehicle does not contains throttle releasingdata indicating the accelerator pedal is being released or the throttlevalve opening is closing, then the process returns back to step S21,where the two-way wireless communication system 21 continues tobroadcast its common message set with its path history message and othervehicle parameters as mentioned above. However, if the control unit 20determines the incoming message of the preceding vehicle containsthrottle releasing data indicating the accelerator pedal is beingreleased or the throttle valve opening is closing, then the process tostep S24, where the throttle releasing data is further analyzed.

In step S24, the control unit 20 determines the degree (high or low) ofrisk of an actual braking situation might occur. In particular, thecontrol unit 20 determines whether the throttle releasing data indicatesthat the accelerator pedal is being released quickly or the throttlevalve opening is closing quickly or closed. In other words, if thepreceding vehicle is releasing its accelerator pedal or the throttlevalve opening is closing, then the control unit 20 compares the throttlereleasing data to prescribed parameters to determine if there is highlikelihood of an actual braking situation will occur in the precedingvehicle. This determination is performed based on one or more vehicletraveling conditions of the host vehicle and/or one or more vehicletraveling conditions of the following vehicle. If the control unit 20determines the throttle releasing data of incoming message from thepreceding vehicle does not indicate the accelerator pedal is beingreleased quickly or the throttle valve opening is closing quickly orclosed, then the process to step S25, where a preliminary warning isgiven to the driver. This preliminary warning can be provided in avariety of ways, e.g., a yellow barking warning can be displayed on thevehicle's windshield via the warning indicator, the steering wheel couldbe vibrated, and/or an audible signal could be produced. However, if thecontrol unit 20 determines the throttle releasing data of incomingmessage from the preceding vehicle indicates the accelerator pedal isbeing released quickly or the throttle valve opening is closing quicklyor closed, then the process to step S26, where an urgent warning isgiven to the driver. This preliminary warning can be provided in avariety of ways, e.g., a red barking warning can be displayed on thevehicle's windshield via the warning indicator, the steering wheel couldbe vibrated, and/or an audible signal could be produced.

After the warning is produced in steps S25 and S26, the control processproceeds back to step S21, where the two-way wireless communicationsystem 21 continues to broadcast its common message set with its pathhistory message and other vehicle parameters as mentioned above. Thus,the process is repeated. Since the incoming messages are coming inrapidly, and then entire process is also completed very quickly, thewarning (if given) will seem continuous to the driver between twoincoming messages that require the same warning. While the illustratedembodiment only shows two warning levels (i.e., yellow and red), it willbe apparent to those skilled in the art from this disclosure thatseveral (three or more) warning levels can be provided if needed and/ordesired.

General Interpretation of Terms

In understanding the scope of the present invention, the term“comprising” and its derivatives, as used herein, are intended to beopen ended terms that specify the presence of the stated features,elements, components, groups, integers, and/or steps, but do not excludethe presence of other unstated features, elements, components, groups,integers and/or steps. The foregoing also applies to words havingsimilar meanings such as the terms, “including”, “having” and theirderivatives. Also, the terms “part,” “section,” “portion,” “member” or“element” when used in the singular can have the dual meaning of asingle part or a plurality of parts. Also as used herein to describe theabove embodiment(s), the following directional terms “forward, rearward,above, downward, vertical, horizontal, below and transverse” as well asany other similar directional terms refer to those directions of avehicle equipped with the present invention. Accordingly, these terms,as utilized to describe the present invention should be interpretedrelative to a vehicle equipped with the present invention. The term“detect” as used herein to describe an operation or function carried outby a component, a section, a device or the like includes a component, asection, a device or the like that does not require physical detection,but rather includes determining, measuring, modeling, predicting orcomputing or the like to carry out the operation or function. The term“configured” as used herein to describe a component, section or part ofa device includes hardware and/or software that is constructed and/orprogrammed to carry out the desired function. The terms of degree suchas “substantially”, “about” and “approximately” as used herein mean areasonable amount of deviation of the modified term such that the endresult is not significantly changed.

While only selected embodiments have been chosen to illustrate thepresent invention, it will be apparent to those skilled in the art fromthis disclosure that various changes and modifications can be madeherein without departing from the scope of the invention as defined inthe appended claims. For example, the size, shape, location ororientation of the various components can be changed as needed and/ordesired. Components that are shown directly connected or contacting eachother can have intermediate structures disposed between them. Thefunctions of one element can be performed by two, and vice versa. Thestructures and functions of one embodiment can be adopted in anotherembodiment. It is not necessary for all advantages to be present in aparticular embodiment at the same time. Every feature which is uniquefrom the prior art, alone or in combination with other features, alsoshould be considered a separate description of further inventions by theapplicant, including the structural and/or functional concepts embodiedby such feature(s). Thus, the foregoing descriptions of the embodimentsaccording to the present invention are provided for illustration only,and not for the purpose of limiting the invention as defined by theappended claims and their equivalents.

What is claimed is:
 1. A vehicle on-board unit comprising: a vehiclepath history generating section configured to generate a host vehiclepath history data indicative of a travel path of a host vehicle equippedwith the vehicle on-board unit in a lane that the host vehicle iscurrently traveling, with the lane being a single lane of a road, theroad having one or more lanes; a two-way wireless communications sectionconfigured to receive a preceding vehicle message that includespreceding cumulative vehicle path history data of at least two precedingvehicle path history data indicative of travel paths of two precedingvehicles in the lane, the preceding vehicles traveling in the lane priorto the host vehicle, the vehicle path history generating section beingfurther configured to create, on-board the host vehicle, updatedcumulative vehicle path history data based on the host vehicle pathhistory data and the preceding cumulative vehicle path history data andthe two-way wireless communications section being further configured tobroadcast the updated cumulative vehicle path history data from the hostvehicle to a following vehicle such that the following vehicle receivesa subsequent message including the updated cumulative vehicle pathhistory data, the following vehicle traveling in the lane subsequentlyrelative to the host vehicle; and a lane centerline determining sectionconfigured to determine a lane centerline of the lane based on theupdated cumulative vehicle path history data, the lane centerlinedetermining section being further configured to weight the precedingcumulative vehicle path history data more heavily than the host vehiclepath history data in determining the centerline of the lane.
 2. Thevehicle on-board unit as recited in claim 1, wherein the two-waywireless communications section is further configured to broadcast adegree of uncertainty indicator associated with the updated cumulativevehicle path history.
 3. The vehicle on-board unit as recited in claim1, wherein the two-way wireless communications section is furtherconfigured to broadcast lane boundary data associated with the hostvehicle path history data.
 4. The vehicle on-board unit as recited inclaim 1, wherein the vehicle path history generating section includesusing GPS data of the host vehicle to generate the host vehicle pathhistory data comprising a plurality of GPS points.
 5. The vehicleon-board unit as recited in claim 1, wherein the two-way wirelesscommunications section is further configured to receive statisticalinformation as part of the preceding cumulative vehicle path historydata; and the lane centerline determining section is further configuredto adjust the host vehicle path history data based on the statisticalinformation and to increase a weight given to the preceding cumulativevehicle path history data in determining the centerline of the lane asthe statistical information includes more vehicle path histories.
 6. Thevehicle on-board unit as recited in claim 1, wherein the vehicle pathhistory generating section is further configured to create the updatedcumulative vehicle path history data based on the host vehicle pathhistory data and only one preceding vehicle path history datum inresponse to only one preceding vehicle history being available, and thelane centerline determining section is further configured to determinethe lane centerline of the lane based on the updated cumulative vehiclepath history data that was created based on the host vehicle pathhistory data and the one preceding vehicle path history datum inresponse to only the one preceding vehicle history being available.
 7. Avehicle on-board unit comprising: a vehicle path history generatingsection configured to generate a host vehicle path history dataindicative of a travel path of a host vehicle equipped with the vehicleon-board unit in a lane that the host vehicle is currently traveling,with the lane being a single lane of a road, the road having one or morelanes; a two-way wireless communications section configured to receive apreceding vehicle message that at least includes a preceding vehiclepath history data indicative of a travel path of a preceding vehicle inthe lane, the preceding vehicle traveling in the lane prior to the hostvehicle; and a lane centerline determining section configured todetermine a lane centerline of the lane based on the host vehicle pathhistory data and the preceding vehicle path history data, the lanecenterline determining section being further configured to weight thepreceding vehicle path history data more heavily than the host vehiclepath history data in determining the centerline of the lane.
 8. Avehicle on-board unit comprising: a vehicle path history generatingsection configured to generate a host vehicle path history dataindicative of a travel path of a host vehicle equipped with the vehicleon-board unit in a lane that the host vehicle is currently traveling,with the lane being a single lane of a road, the road having one or morelanes; a two-way wireless communications section configured to receive apreceding vehicle message that at least includes a preceding vehiclepath history data indicative of a travel path of a preceding vehicle inthe lane, the preceding vehicle traveling in the lane prior to the hostvehicle; and a lane centerline determining section configured todetermine a lane centerline of the lane based on the host vehicle pathhistory data and the preceding vehicle path history data, the two-waywireless communications section being further configured to receivestatistical information as part of the preceding vehicle path historydata, and the lane centerline determining section being furtherconfigured to adjust the host vehicle path history data based on thestatistical information and to increase a weight given to the precedingvehicle path history data in determining the centerline of the lane asthe statistical information includes more vehicle path histories, thelane centerline determining section being further configured to weightthe preceding vehicle path history data more heavily than the hostvehicle path history data in determining the center line of the lane. 9.A lane centerline determination method comprising: generating a hostvehicle path history data indicative of a travel path of a host vehiclethat has traveled in a vehicle lane, with the vehicle lane being asingle lane of a road, the road having one or more lanes; receiving apreceding vehicle message that includes preceding cumulative vehiclepath history data of at least two preceding vehicle path history dataindicative of travel paths of two preceding vehicles in the lane, thepreceding vehicles traveling in the lane prior to the host vehicle;generating, on-board the host vehicle, updated cumulative vehicle pathhistory data based on the host vehicle path history data and thepreceding cumulative vehicle path history data; broadcasting the updatedcumulative vehicle path history data from the host vehicle to afollowing vehicle such that the following vehicle receives a subsequentmessage including the updated cumulative vehicle path history data, thefollowing vehicle traveling in the lane subsequently relative to thehost vehicle; and determining a centerline of the vehicle lane based onthe updated cumulative vehicle path history data, the determining of thecenterline of the vehicle lane including more heavily weighting thepreceding cumulative vehicle path history data than the host vehiclepath history data in determining the centerline of the vehicle lane. 10.The lane centerline determination method as recited in claim 9, whereinthe broadcasting of the updated cumulative vehicle path history dataincludes broadcasting statistical information relating to the precedingcumulative vehicle path history data, and the determining of thecenterline of the lane includes using the statistical informationrelating to the preceding cumulative vehicle path history data to adjustthe host vehicle path history data in determining the centerline of thevehicle lane.
 11. The lane centerline determination method as recited inclaim 9, wherein the broadcasting of the updated cumulative vehicle pathhistory data includes broadcasting lane boundary data associated withthe host vehicle path history data of the host vehicle.
 12. The lanecenterline determination method as recited in claim 9, wherein thebroadcasting of the updated cumulative vehicle path history data furtherincludes broadcasting a degree of uncertainty indicator associated withthe updated cumulative vehicle path history data.
 13. The lanecenterline determination method as recited in claim 9, wherein thegenerating of the updated cumulative vehicle path history data is basedon the host vehicle path history data and only one preceding vehiclepath history data in response to only one preceding vehicle historybeing available, and the determining of the centerline of the vehiclelane is based on the host vehicle path history data and the onepreceding vehicle path history datum in response to only the onepreceding vehicle history being available.